Power hammer



2 Sheets-Sheet l l.. sKEEL ET A1.

POWER HAMMER Filed sepi. 19, 1929 March 14, 1933.

' March 14, 1933. l.. sKEEL ET AL POWER HAMMER Filed Sept. 19. 1928 2 Sheets-Sheet 2 Syvum/101,5 jeu/1.5 fee l;

Patented Mar 14, 1.933

Lnwrs sKEnL AND FRANK' P. MILLER, or MEADVILLE, PnNNsYLvANiA, AssIG'oRs To i/rcCRosKY 'rooL Connor-ramon, on MEADVILLE., PENNSYLVANIA, A @citronn- TION F PENNSYLVANIA POW'ER HAMMER Application filed September 19, 1928. Serial No. 306,955.

A hammer constructed in accordance with this invention will be found to embody means by which the reciprocation of a driving piston K is imparted to a freely movable striking ele- U ment through the alterna-te compression and rarefication of the air between these two bodies and to provide for the automatic replenishment of such supply of air at regular intervals to maintain a constant and fully J operative relation between the driving piston and the striking element whereby to utilize to the greatest advantage the power of the hammer except, of course, when the hammer is intentionally idled.

Another attribute of the invention resides in the means by which the air alternately admitted to and discharged from the cylinder of the hammer may be completely isolated to avoid contamination thereof by the surrounding dust laden air, in consequence of which the moving` parts of the hammer are protected against excessive wear.

The herein described hammer further proides for the lubrication of the supplemental air chamber in one of the motion transmitting members, such as the driving piston, first, to reduce the friction incident to the movement of a piston-like extension of the other motion transmitting member into said chamber and the engagement of the extensionwith the wall of the chamber and second, to aid in the establishment of a substantially air tight seal between said extension and the wall of the chamber, the open end portion of said chamber being slightly flared to deine a gradually restricted entrance opening by which said extension is guided accurately into the supplemental air chamber.

0 The invention further embodies a novel tool holder which may be detachably connected to the cylinder of the hammer and which is designed to hold'the tool, such as a star drill, in proper position and to be freely removable.

@ther objects and advantages will be apparent during the course of the following description.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a vertical sectional view through the hammer 1n an idle or neutral position,

Figure 2 is a fragmentary longitudinal sectional lview through the hammer in an operative position,

Figure 3 is a detail sectional View illustrating a slight modification of the invention,

Figure Ll is a sectional view taken on line l 4 of Figure 3,

Figure 5 is a vertical sectional view through another modication of the invention,

Figure 6 is a transverse sectional view taken on line 6--6 of Figure 5.

Figure 7 is a transverse sectional view taken on line 7-7 of Figure 5,

Figure 8 is a transverse sectional view taken on line 8-8 of Figure 5.

` ln the drawings the numeral 10 designates a cylinder preferably of bronze and having the rear portion thereof threaded into what might be said to be the attaching portion 11 of a housing 12. The attaching portion 11 and the adjacent portion of the cylinder 10 are provided with radial openings adapted to be brought into registration for the reception of a fastening screw 14 by which the cylinder` is held against turning with respect to the housing.

In carrying out the invention a more or less conventional motion transmitting mechanism is located within the housing 12 and comprises in part, spindles 15 and 16 having similar counterbalanced disks 17 to which the wrist pin 18 of a short connecting rod 20 is attached. Suitable anti-friction elements 22 and 2e rotatably support the spindles 15 and 16 respectively. The anti-friction element 22 is shown to be carried by the closure plate 26, while the anti-friction element 24 is carried by the housing 12. It will be seen that the axial bore of the spindle 16 is provided with transverse pins 28 with which the terminal linl; of a flexible driving chain or the like may be operatively engaged. Any suitable source of power, such as an electric 100 motor, may be employed to operate the hammer.

The connecting rod is swiveled to a driving piston or element having a rather close i'it within the cylinder and adapted to bring about the reeiprocation of a driven or striking element 32 also located within the cylinder.

An axial open ended chamber 34 is formed in one of 'the movable elements within the cylinder l@ and is adapted to snugly receive an axial piston-like extension 36 of the other movable element to compress the air therein so that when the piston 30 moves on its forstrokc the driven element 32 will be catapulted forward into striking engagement with the sha k of the tool 33. The open end portion of the chamber 34 will be found to be slight y flared to define a gradually restricte f. entrance opening for the reception of the piston-like extension 3G. To allow the driven or striking element 32 freedom of movement to respond to the various forces to which it is subjected the same has been made slightly less in diameter than the diameter of piston 30, and thus the slight flare at the open endL of the chamber 34 will guide the piston-lil-:e extension 3G into the chamber and the members 30 an d 35 with each other.

rhe fit of the piston-like extension 36 in the chamber 34 is close one and the opposed walls of the chamber and the extension 3G jrcove 39 in the peripheral portion of the iving piston. l portion of the lubricant supplied to the anti-friction elements and he moton transmitting mecnanism within `he housing l2 will lind its way between the of the cylinder l() and the piston 30 and be received in the circumferential groove 39 for into the chamber 34 to reduce friction incident to the entrance of the extension into the chamber, and at the same time to aid in the blishmcnt of an air tight seal between the extension and the wall of the chamber 34.

Thus, the etension 3G is allowed free entrance into the chamber to compress the air therein so that on the subsequent forward ke of the piston the air previously compressed within the chamber will be further compressed and caused to atapult the striking` element 32 into engagement with the shank of the tool. The main body of air between the driving and driven elements 30 and 32 respectively will function very much the same as the air trapped within the chainber 34 and in addition will be rareiied to some extent on the rear stroke of the piston 30 to more the striking element 32 rearward or to act in concert with the rebound of the strikiiw element in doing so.

It will be seen that tie supply of air between the driving and driven elements is subject to depletion by leakage incident to compression thereof and to provide for the intermittent replenislnnent of this supply of air the cylinder l0 has a port that is uncovered during only a short portion of the stroke of the striking element. Actual use of a hammer constructed in accordance with this invention has demonstrated the fact that the volume of air admitted to the space between the elements 3() and 32 by way of the port is merely su'lcient to provide for the ellicient operation of the hammer and does not interfere with the initial phase of the rear str ke of the striking element. 0f course, afte the port 44 is closed on the rear stroke of the striking element it remains inoperative until the striking element again approaches the limit of lforward movement thereof.

From the foregoing, it will be seen that the air supplied to the cylinder l0 by way of the port compensates for the partial loss of air resulting from the compression of the same and thereby maintains a constant operative relation between the driving and driven elements as distinouished from previously known hammers ir which a forceful blow was impossible because of the reduced supply of air available for compression after the hammer has been in use a short period.

The cylinder l0 is shown to be provided in advance of the port 44 with a separate series of ports 46 by which air may be admitted to the space between the driving and driven elements to intentionally idle the hammer. rlhat is to say, when the striking element 32 is in its foremostor idle position as shown in Figure l the ports 46 are uncovered to allow a fully neutralizing supply of air to be admitted to and discharged from the cylinder during the reciprocation of the driving piston 30. During the reciprocation of the element 32 the ports 46 remain entirely closed.

By moving the striking element 32 back across the idling ports 46 the full power of the hammer is brought into play. This may be accomplished by moving the hammer vforward until the tool 33 connected thereto has pressure engagement with the work and the tool in turn, caused to move the striking element backward.

The shank of the tool is extended through and is shouldered against a bushing 43 movably mounted within a casing 49 and urged to an extreme forward position by a spring 50. rlfhe rear end ofthe casing 49 is flanged inward to form a stop for the spring and at the same time to guide the shank of the tool. lt will be seen that the resistance of the spring 50 must be overcome to bring about the rearward movement of the striking element across the ports 46. Also, the spring 50 makes it possible to graduate the force of theblow.

The casing 49 is detachably mounted within the cylinder l0 and is held in place against a shouldered portion of the cylinder by a tool holding nib 52 threaded into the cylinder and locked in place by a fastening screw The forward terminal of the screw 53 may be extended into the bore of the nib 52 to cooperate with an adjacent flat on the shank of the tool in holding the tool against turning. As previously stated, the cylinder l0 is preferably of bronze, while the tool holding parts are of hardened steel and are freely removable for inspection and repair and for gaining ready access to the striking element.

fis illustrated in Figures l and 2, a jacket 58 is mounted on the cylinder in spaced relation to a substantial portion of the same and cooperates therewith in the formation of an annular reservoir in constant communication with the ports dat, 46 and the ports 59 so that the air alternately admitted to and discharged from the spaces between the driving and driven elements and immediately in advance of the striking element is substantially isolated to avoid contamination thereof by the surrounding air. The rear portion of the acket 58 is in constant communication with passages or ducts 60 in opposite sides of the housing l2 and the ducts in turn communicate with the opposite ends of a chamber or passage Gl extending through the handle 62. lt will be seen that the passages 60 and 6l greatly augment the capacity of the reservoir and that the air which travels through the handle has a cooling effect thereon.

lf the particular use to which the hammer is put does not create dust the closure 64 of the passage 6l may be removed to open the reservoir to the atmosphere.

ln the Figures 3 and L the cylinder is provided with an annular series of -combination replenishing and idling ports 72 designed to be uncovered, in whole or in part, by the striking or driven element 70. ln explaining this it is pointed out hat when the striking element is in foremost or idle position all of the ports 72 willl e uncovered to admit air in sufficient volume to the space between the driving and driven elements to idle the hamml.

@n the other hand, when it is desired to forcefully reciprocate the element 70 the same is moved rearward to cut off the idling supply of air. rl`he driven element 70 is formed with transverse and longitudinal connected passages, the transverse passage 7l be'ag adapted for random communication one of the ports 7 2 for a short portion of each stroke of the driven element so that the supply of air between the driving and driven elements is replenished in the proper volume at each stroke of the hammer. rlhe form of invention illustrated in connected to the housing 8l by an attaching member S2 to which a acket 83 is connected for limited rotation. The rear portion of the jacket 88 is provided with a circumferential slot 86 receiving a fastening screw 87 by which the jacket may be held in a fixed position. As shown in Figure 7, the attaching portion 82 and the jacket 83 are provided with ports 88 adaptable for mutual registration so that the reservoir defined between jacket 83 and the cylinder 8O may be opened A.

to the atmosphere. On the other hand, the sleeve 83 may be rotated slightly to close the ports 88 and may be secured in this position by the fastening device 87. rlhe forward portion of the jacket is mounted on a supporting annulus 9G carried by the adjacent portion of the cylinder 80.

The driven element 92 shown in Figure 5 is provided with a chamber 99 adapted to snugly receive the liner 94 of the driving piston.

The stem 96 of the driving piston has the rear portion thereof connected to the rod 9T by a ball and socket joint 98 positioned within the body 99 of the piston approximately midway of the ends thereof to provide for the eliicient transmission of power. rlfhe stem 96 of the piston is extended through the liner 94 and has the forward portion thereof upset so that the members 94, 96 and 99 have the e'liect of one single body.

Having thus described the invention, what is claimed is:

l. In a hammer, a cylinder, a driven element in the cylinder, a reciprocatingdriving piston in said cylinder and serving to alternately compress and rarefy the air between the same and the driven element whereby the reciprocation of the driving piston is imparted to the driven element, said cylinder being provided with means spaced from the driving piston and uncovered by the driven element only upon reaching the forward portion of the forward stroke of the driving piston and as a preliminary to the rear stroke of the driving piston by which the supply of air between the driving piston and said driven element is replenishedduring a short portion only of the strokes of the vdriving piston and the driven element.

2. In a hammer, a cylinder, a driven element in the cylinder, a driving piston in the cylinder and serving to compress the air between the same and thedriven element whereby the forward movement of the driving piston is imparted to the driven element, said cylinder being provided at a point adjacent to one end of the stroke of the driven element and at a point spaced from said driving piston with a port adapted to be uncovered by the driven element` only during the completion of the forward stroke thereof and as a preliminary to vthe rear stroke of the driven clement to replenish the supply of air between the driven element and the driving piston, the aforesaid supply of air being otherwise isolated during actual use of the hammer.

3. In a hammer, a cylinder, a driven element inthe cylinder, a driving piston in the cylinder and serving to intermittently compressthe air between the same and the driven element whereby movement of the driving rpiston is imparted to the driven element, said cylinder :being provided at a point adjacent to one end of the stroke of the driven element and at a point spaced from said driving piston with a port adapted to be uncovered by the driven element during a short portion only of the stroke of the driven element, and as a preliminary to the rear stroke of the driven element to replenish thek supply of air between the driven element and the driving piston, the aforesaid supply of air being otherwise isolated during actual use of the hammer, said cylinder being provided with a second port spaced from the first named port and adapted to be uncovered by said driven element` to admit and discharge a substantial volume of air to neutralize the action of the driving piston and thereby idle the hammer.

4. In a hammer, a cylinder, driving and driven elements mounted for reciprocation in Athe cylinder, the movement of the driving element serving to intermittently compress the air between said elements and actuate the driven element, and a jacket surrounding said cylinder in spaced relation thereto to cooperate therewith in the formation of a closed chamber, said Cylinder being provided with a port communicating with said closed chamber and adapted to be uncovered by the driven element during the completion of the forward stroke of the driven element and as a preliminary to the rear stroke of the driven element to allow the supply of air between said elements to be replenished at each stroke of the same.

5. In a hammer, acylinder, a driving piston in the cylinder, a driven element freely movable in the cylinder and being slightly lessened in diameter than the driving piston` said driving piston being provided with an open ended axial chamber and with a peripheral oil collecting groove in constant communication with the chamber ro suppl,l oil thereto, said driven element being provided with an axial extension adapted to be snugly received in said chamber.

`6. In. a hammer, a cylinder, a drving piston inthe cylinder, a driven element of cylindrical form freely movable in the cylinder and having a diameter slightly less than that of the piston and being provided with a reduced axial extension, the driving piston being provided with an open-ended chamber slightly enlarged at one end to guide said extension into the chamber, said driving piston also being provided with an annular oil collecting ,groove and radial ports establishing constant communication between said groove and said chamber to furnish a lubricant tothe chamber.

In testimony whereof we affix our signatures.

LEW'IS SKEEL.

FRANK P. MILLER. 

